Richard,
I didn't mean to finger you in particular, just trying to quell the
massive misinformation that seems to be flying these wires. We are
having a violent agreement.
Dave
Richard B. Gilbert wrote:
David L. Mills wrote:
Richard,
Really and truly do believe interpreting stratum as quality of service
is a bright red herring. It was never intended for that purpose. Its
primary purpose is avoiding timing loops. There is an absolutely
wonderful metric with which to interpret quality, a combination of
maximum error (synchronization distance) and estimated error (system
jitter). There are explicit provisions in the reference clock
interface that allow the driver to adjust these values with respect to
whatever statistics the clock provides. It would seem the PDoP
commonly provided by the GPS receiver firmware would be a prime
candidate.
Dave
Richard B. Gilbert wrote:
<snip>
I don't think of stratum as an "estimate" of goodness. I think it's
purely a designation of position in the hierarchy. A stratum one
server is stratum one because it gets its time from a primary
standard; e.g. an atomic clock. A server that gets its time from a
WWV receiver is technically stratum one and can be several
milliseconds off because of the vagaries of HF radio propagation.
The "goodness" of a server also depends on the path through which you
receive time from it. A client that is three thousand miles away
from a stratum one server and receiving time over a heavily used
network is probably getting time that is an order of magnitude
poorer than a client three hundred feet away.
Fudging a server to a higher stratum than it would normally have
should make it appear less desirable to any client that has a choice
of servers.
I hope I didn't create the impression that I was arguing the opposite!!
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